linux-kernel - Re: [PATCH v3 02/11] arm64: Make use of is_compat

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Message-ID: <CAGXu5jKVa2YgAkWH1e26kxd2j6C4WsJ38+Z3K1z7JRvr_jDX6Q@mail.gmail.com>
Date:   Wed, 17 Apr 2019 23:32:17 -0500
From:   Kees Cook <keescook@...omium.org>
To:     Alexandre Ghiti <alex@...ti.fr>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-mips@...r.kernel.org, linux-riscv@...ts.infradead.org,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH v3 02/11] arm64: Make use of is_compat_task instead of
 hardcoding this test

On Wed, Apr 17, 2019 at 12:25 AM Alexandre Ghiti <alex@...ti.fr> wrote:
>
> Each architecture has its own way to determine if a task is a compat task,
> by using is_compat_task in arch_mmap_rnd, it allows more genericity and
> then it prepares its moving to mm/.
>
> Signed-off-by: Alexandre Ghiti <alex@...ti.fr>

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  arch/arm64/mm/mmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
> index 842c8a5fcd53..ed4f9915f2b8 100644
> --- a/arch/arm64/mm/mmap.c
> +++ b/arch/arm64/mm/mmap.c
> @@ -54,7 +54,7 @@ unsigned long arch_mmap_rnd(void)
>         unsigned long rnd;
>
>  #ifdef CONFIG_COMPAT
> -       if (test_thread_flag(TIF_32BIT))
> +       if (is_compat_task())
>                 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
>         else
>  #endif
> --
> 2.20.1
>


-- 
Kees Cook